Motor-driven blowoff valve



Oct. 28, 1952 w. c. SCHOFIELD 2,615,459

MOTOR-DRIVEN BLOWOFF VALVE I Filed May 4, .1946 2 SHEETS-SHEET 1 VIII/IIIIIIIIII/IIIA L i U Fi 3'. I

INVENTOR.

LUi Zfred C. .S'chaf'ield o 1952 w. c. SCHOFIVELD ,61

MOTOR-DRIVE BLOWOFF VALVE Filed May 4, 1946 2 suEE'rs-sm'm INVENTOR.

(Ui lfred C. SChOfie Zd Patented Oct. 28, 1952 Wilfred c. Schofield, chic-agar.nigisisigmmy .mesne assignments, to Koppers Company,- Inc.,

a corporation of Delaware 6 j Application M y-4, 1946, Serial no: 667,451

1 claim.- (01. 137-4103;) M

The present invention relates to'improvemerits in'blow-ofi valves.

Moreparticularly, the present invention relates "to improvements in blow-off valves such as used in connection with blast furnace stoves.

A blast furnace stove is operated alternately "to heat 'air being delivered to a blast furnace, the heat for the purpose being stored'in checkerbrick or the like within the stove; During other periods the checkerbrick within the stoveis heate d' byburning-blast furnace gas within the stove;

' "At times when the stove'is on blast the pressure 'in -thestove may range from one to three at- 'mo's'pheres"above atmospheric pressure. When thestove is on gas, that is; while the stove is being' -heatedl; the pressure within the stove is commonly approximately atmospheric. a 1' When thestove is being changed from air to ga'sfthat is, when it has given up itsheat and is'to be heated, the valve connecting the stove to the source of cold blast is closed and the hot blast valve connecting the stove to the blast fur- Inac'eis closed. As noted above, the pressure within thei'stoveis substantially above atmospheric audit is' necessary'to' discharge theairfrom "the stove underconsiderable pressure; .Itis'a function of the blow ofi valve to relieve the stove by discharging this air to the atmosphere.

An object of the present invention is to pro- .lvide an improved blow-01f valve-having thead- -vantage that it is unnecessary that the operat- .in g.- means therefor be stopped exactly at avpredetermined position. V A iurther object is to provide an improved blow- 6 off valve involving a mechanical movement havi ng the characteristics-of a toggle.

5 A further object is to provide an- ,-1mproved blow-ofi' valve-in which it is unnecessary-to pro- ;yide a brake. a v o. p d further'object is to provide an improved .blow +ofi valvehaving the advantage that at the g start of opening movementof the valve discpthe driving' means has a large mechanical advantage whereby it may force the disc open'against a substantial pressure. 7 v

# A-iurther object is to provide a'blow-off valve havingthe advantage that a motor, for operating said valve may havea flying start,'enabling the motor to gain momentum before it is required -to start the opening movement of the valve dis-c.

further object is to provide an improved blow-01f valve which is simple and sturdy in construction and not likely toget out of order;

A further object is to provide an improved 'p1'0ceeds.1 :f"- a Referring .to'ithedrawings: i

Figure .1. is aiview in. s'ideaelevation, parts being 1 presentinventi on; and p i *Figurez is 'a viewin'erideleva'tion ofvthe struction of a .blow-oif' valve.

met-Oil valve wen adapted to meet, tastes of 'commer'cialiserviel Further: objects will; appear as the descr ption broken away, illustrating one embodiment of the ture illustrated in Figure l.-

i The numeral 10' 'ndicates themainrbo'dyipor- Said. bodyporiti'oh' has connected thereto a pipe l l Whichmay lead to a hot blast stove; A pipe I 2 leading to "said body ..portion may befcbnnectedto the. atmosphere. i The body portion: l0includes"the'conduit por- --tion l3 which isiillust'rated as being in the form of an elbow,;:one end'being connectedito-thever- 'tically disposed pipe l2 and the other end being connected. to the horizontally disposed :pipefill saidiconduit portion adj acent'to-rpipe .H is flanged as'indi'cated by numeral 14 and is provided with thexreplaceablewalve seat [5 having a circular aperture" bounded at its outer extremity" byra conical:portion"adapted to receive 2; correspondin'g conical portion of the valve :disc" 16;: Said Lvalve disc '|6"is loosely and resiliently carried by the valve stem I 1, which valve stem' -is'ghorizontally disposed and is carried. by thezsupporting portion 18 rigidwith the body portionrll'l;

- The casting which 'comprises the body-portion 10 of the valve is open at the side-:thereof o posite ;to} the flange: Ht; this opening" being 6 covered rby the :housinglt: The outer extremity of the housing [9 is provided withthe aperture 2 0: closed by means: of theremovable cover plate'2 l;-- q The valve jstem; .l 1.. slides withinib'earirigs; one 'of whichis indicatedibyxnumeral 22 5 F The-end of the "stem l'l opposite-toxdis'c "It is providedwith the crack portion 23 "adapted: ;,to 'havelca sliding movement along the floor'of the-housingPl-il.

" The .upper'side of the rack portion 23xis' provided with teeth .2 5 -25 adapted to be""engaged"bytthe .te'eth of a: pinion 26 which will be referred to more in detail presently. J t 1::

The valve stem I 1' adjacent to its left'extremity is reduced in. diameter as indicated byjj numeral v2",iorming a shoulder 28 having abuttingrelaiti'onship with the boss 29 forming part of the ,valve."disc.il6'.-. I Said boss 29 is centrally apertured arid is'adapte'dto have a reciprocating'anda slight rocking movement with re'spect tothe' ife- -duced portion 21 of the valve stem 11: The'valve stem Il at its left 'extremity,1as the parts are viewed in Figure 1; is'pro'vid'ed with the nut'3ll and disposed upon the reduced portion 21 between the nut 30 and the boss 29 is the spring 3!, which spring has the function of resiliently urging the boss 29 against the shoulder 28 of the valve stem l1. Numeral 32 indicates a cup-shaped member secured to the outer surface of the valve disc l6 and providing a cover to prevent leakage past the valve stem.

Mounted-'at-the top of thevalve body Hlis-a mounting member 33 which supports a driving motor 34, an operating shaft 35, and a train of gearing (not illustrated) between-saidmotor-and said shaft 35. The numeral 33 indicates a hand wheel which may be conne'ctedito ssaiditrainv of gearing at an intermediatepoint thereinwhereby movement of the valve disc l6 may be accom' plished manually, the number-sof-:turnsofthe hand wheel being restricted to a practical value.

The connection between the shaft 35 andpinion- 26 may be described as follows. The pinion 26 '11is:-"carried' by.1shafti which? has keyed thereto the crank 38. The shaft 35whasrgearedsthereto i'thertcrank' 39. The' swinging extremities of the cranks 38 and 39 are connected togetherby-means of the rod 40. Preferably-the rodMJwill-beof a rlength to permita complete rotation of crank 39-. :Rotation of'the'crankr38-"wi1l be limited to' an angle of approximately ninetydegrees; this angu- --la'rity being limited byuthepermissible movement of rack member 23.. In rotating the crank-38* through.approximately ninety degrees the crank .33 will' turn through a maximum-of one hundred andieightysdegrees. =With this arrangement it-is possible-to:cpetrrand close'the valve disc'lii with eitherl:directionfofr-rotation-of the shaft 35, and over-travel pnzf'the: *part: iof; the? shaft "35 will do :nd'harmLiIf the cranki39 iravels past dead cen- -tecit simply reverses the valve action. .zfBy reasonsf'of: the loose and" resilient connection between ithei valveistem "land-the valvedisc (6 1 :a'rocking .movement 'offsaidvalve disc is permitted after ithas' reached its seat. ":In view of the per- 'imissible zaxial'rmovement between the stem'" fand' the'xvalvesdisc13,2it iszunnecessary to have --accurate"stopping iof the-valve drive" mechanism. 4

l the numeral 4 lindicates as a whole a limit switch foricontrolling the motor 34, "which limit switch 'is connected to the shaft 35 'through a pair of bevelgears 42'-42.

The -mode o'f operation of the above described embodiment of the: present invention is substan- -tially asfollows:

wrdinarily it will" probably be'preferred to oper- 'iat thei 'shaft 35 in'a counter-clockwise direction ias the-partsiiare viewed inFigure 1) for closing valve disc' :16. Figure 1 illustrates in full lines a cdesiredtpositionpfthe two cranks 33 and 39 when "ithe iva'lve disc I6 just touches its'valve seat, no rr'elative movement .having'yet taken place be- ':-'-tween valve? stem '11 and valve disc l6. At this; pointi the. limit switch H will de-energize the rmotor -34..and the'inertia of the mechanism-will ocause' the crankrilfi to move further, thereby comepressing the valve spring 3! and increasing the braking load on the motor 34 until the mecha-=. mismnstops. .It. is unnecessary to have accurate .'"stopping of the'valve drive mechanism. Furtherm'ore; the 'compression of spring 3|. increases the :iloadzon'the drivemechanism as soon as the valve "discf'seats. Thisv causes the me'chanism'to stop" without the necessity ofa mechanical brake. .The tensionwof spring 3|- will be adjusted to increase the load sufficiently to stop motor 34 before the @mechanism passes dead center and starts to open izthe'valveafter acompletaclosure.

4 In opening the valve disc 16, the crank 39 will be moved in a clockwise direction through approximately one hundred and ten degrees to the position indicated in dotted lines in Figure 1. 5 At this point the limit switch 4! will cut off the power supply to the motor 34 and the mechanism will drift to rest, retarded only by the friction in "the drive equipment. The crank 39jwill' actually i come to" restapproximately at itsdead center position and the valve disc I6 will be at its maximum open position. However, it is unnecessary ....for the crank 39 to stop at dead center as the "valvewillbpenadequately with the crank 39 at anyfmosition up 'to'approximately forty degrees 'on eitherriside 'ofldead center position.

' The' Cranks BEi-and 39 and the rod 40 comprise apower transmitting linkage having the characteristics of a toggle and the driving crank 33 is near its dead center positions at the two extremities of travel of the rack member 23. This makes it unnecessary that-the motor be stopped exactly and it permits omission of a blflkBythSfiDPI'OXimate toggleaction of the crank 39 servingincom "nection with the---worm gear drive--- to hold the valve in its open-position.

Theabcve describedembodiment-of the present invention has the-advantagethat at the start-0f .the opening movement ofthe valve disclfi -the -motoi- 34 has a large mechanicaladvantage so that-it is able to force the disc 'open-against a substantial pressure. The fact that -spring M has been previously compressed enables the motor 'toget a flying start before the motor is -required .to start the opening movement'of: the-valve disc. 35 ..-As' indicated above, the mechanism --maybe operated independently of motor 34, the hand wheel-36 being provided I for manual operation. Inasmuch as-said hand wheel-36 is-connected to an intermediate point in the train-of -ge'aring 40 between the motor 34 and the shaft 35 the number of turns of the hand wheel required for oper- 'ationof shaft 35 maybe'restrictedto a practical value. Though a preferred embodiment of the present invention has been described in detail 'many'modifie'ations 'will occur to those skilled in the art. It'is-intended to cover all such modifications that fall within the scope of the appended claim.

:Wh'at'is claimed is: v 5 :Inxa'blow-offvalve for the release of gases under superatmospheric pressure from J the in- -teri'or"of a hot blast furnace stove to the atmosphere after a blast period, in"combin ation, a housing having a valve seat,-a valve disk for said 5 -seat, a 'reciprocable' stem loosely carrying "said disk,'-said*stem being provided with a-spri-ng for resiliently urging'said disk longitudinal-1y with respect to said stem, a rack and pinion drive for longitudinallymcving said stem, said valve disk being positioned on the opposite side of 'said valve seat from said rack and piniondrive, said spring being positioned to urge said valvedisk-toward 'said rack and pinion and' toward said valve seat by the longitudinal movement of's'aid stem during the closing of the valve, to becompressed by the longitudinal movement of=said stem during the final stage of'valve closing and toibe' released from compression during the first 'stage of movement of"said"stem' to open said "valve, a crank'for activating" said rack and pini'on drive, an" operating crank; a ri'gid rod'pivotally attached to and'connecting the'swinging extremities of said cranks, and a'mot'or for operating said operating crank, 'said cranks,"rod, 75 'valvewdisk; valve stem and motor being adapted to cooperate with said spring so that said spring will give said valve disk and valve stem a flying start by the release of compression thereof upon initiation of the movement of the valve stem to open the valve at the same time that said cranks and rod are in a position to exert the greatest mechanical advantage and hence the greatest force for opening said valve and will act as a brake to brake said motor and as a cushion to prevent valve damage by the compression thereof during the final stage of valve closing when the cranks and rod are in a position to exert the greatest mechanical advantage for asserting the greatest force for closing said valve and for transmitting the braking action 16 2,453,771

of said spring to said motor.

WHIFRED C. SCHO'FIELD.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,421,800 Mars July 4, 1922 1,467,214 White Sept. 4, 1923 1,494,808 Rousseau May 20, 1924 1,695,452 Carnes Dec. 18, 1928 1,924,377 Pontow Aug. 29, 1933 2,052,987 Persons Sept. 1, 1936 2,280,062 Craig Apr. 21, 1942 2,365,927 Allen Dec. 26, 1944 White Nov. 16, 1948 FOREIGN PATENTS Number Country Date 210,387 Switzerland of 1940 

